The Proteax
module of iScienceSearch provides an easy way to perform
substructure and structure similarity searches in major Internet
databases containing peptides, such as PubChem, CheBI and ChemSpider
starting from plain 3-letter-code peptide sequences.

When
performing real structure searches, you can find peptides containing
structure modified amino acid residues. These cannot be found using
strictly text based searches such as BLAST.

You can also
search generic text terms in PubChem and CheBI and end up on a
result page that only contain structures that are peptides or
peptide like structures such as Penicillin.

In order to analyze the
results easily, we transform the complex structures back into
the 3-letter-codes. We show structures when we cannot map back to
the natural amino acids, see the picture below.